Nindalf

The great marshland region beneath the Emyn Muil that formed opposite the wide delta where the river Entwash flowed into the Anduin.

Notes

1

The name Nindalf is never explicitly explained, but nin is definitely 'water' and dalf is an old Elvish word for a wide flat area or field. As additional confirmation, we have the Common Tongue equivalent 'Wetwang', where wang means 'field', so this interpretation seems relatively secure.